After an egg is fertilized, cells begin to divide. All the cells have exactly the same genetic information as each other. The mystery was how embryonic cells later know to separate themselves into skin cells, brain cells, and so on.
Dr. Claudio Stern is an embryologist at the University College, London in the United Kingdom. Stern’s team has observed a process in chicken embryos by which cells at one end of the embryo act differently from cells elsewhere in the embryo. Only at one end of the embryo, some cells pile up on top of each other. This different behavior provides a driving force for other cells to move and ultimately “know” what sorts of cells to become.
Claudio Stern: So what we’ve uncovered there is a mechanism by which cells at one end of the embryo undergo a different behavior from the rest. That positions a group of cells, and sends signals between one group of cells and others to the center of the embryo where the business end is going to happen.
Stern said the next step will be to find out what makes some cells go to the inside of an embryo to make internal organs, while others stay on the outside to give rise to skin and so on. This work brings us a step closer to understanding life on Earth.